In construction, air barrier systems are the unsung heroes of building envelopes. While not as flashy as curtainwalls, they quietly ensure buildings remain comfortable, efficient, and durable. Think of them as the building’s undergarments – essential for performance, even if not on display.
An air barrier system comprises materials and components that control airflow between a building’s conditioned space and the outside. Unlike insulation or vapor barriers, air barriers specifically target air movement through the building envelope. They can be made from membranes, fluid-applied barriers, rigid panels, or spray foams. Continuity is key; an effective air barrier must form an uninterrupted boundary, sealing all joints and penetrations.
Without proper air barriers, buildings would constantly feel drafty, leading to energy loss and higher costs. Air leakage forces HVAC systems to work harder, increasing energy bills. If you live in an older home, you are likely used to this phenomenon. Studies show that air barriers can reduce energy costs by up to 40%, offering a quick return on investment.
Imagine trying to fill a bathtub with the drain open. Air barriers effectively “plug the drain,” ensuring energy investments serve their intended purpose.
With less air leakage, HVAC systems operate more efficiently, reducing wear and tear. This can extend equipment life and possibly allow for smaller-capacity systems in new constructions, lowering upfront costs.
Moisture intrusion is also a significant threat to building durability. Air leakage can lead to condensation, promoting mold growth and if left untreated structural damage. Effective air barriers prevent these issues by keeping materials dry, preserving structural integrity.
Another advantage to air barriers are in colder climates, they protect against freeze-thaw cycles that damage masonry and concrete. By limiting air movement and acting as a moisture mitigation layer, they keep materials drier, reducing vulnerability to damage.
Arguably the largest benefit though is with indoor air quality. We spend large portions of our time indoors, making air quality crucial. Air leakage allows pollutants and allergens inside. Air barriers act as a shield, keeping contaminants out and creating healthier environments.
By preventing moisture issues that lead to mold, air barriers eliminate a major source of indoor pollution, benefiting those with allergies or respiratory conditions.
Comfort isn’t just about temperature settings or making sure there are no pollutants. Drafts and cold spots can make spaces uncomfortable. Have you ever been in an old house or building and need a sweatshirt in one room and shorts and a T-shirt in a another? Air barriers eliminate these issues, maintaining consistent temperatures throughout the building.
Consistent thermal environments allow for comfortable settings, enhancing energy savings and occupant satisfaction.
All of these great benefits from one layer of “undergarments”! Why don’t Codes require them? That’s a fantastic question, and the answer is building codes do increasingly mandate air barriers. Installing them ensures compliance and helps positions buildings for green certifications like LEED, offering market advantages.
As energy efficiency standards tighten, buildings with air barriers are better positioned to meet future requirements without costly retrofits. This future-proofing is a form of insurance against compliance costs.
While all of this sounds fantastic, and is an easy decision on a new building, installing air barriers on existing buildings is a challenge. It often involves removing the existing exterior cladding or finishes and installing the barrier before installing new cladding. It is an expensive process that should be planned out by a design professional. As mentioned above, the benefits are tremendous, but in urban environments where accessing high rises is often the biggest cost, it can be cost prohibitive. However as more laws are enforced such as NYC LL97 and Boston’s BERDO, it will become necessary to install. Buildings should start planning now to ensure they can reach their carbon reduction requirements on time, and help ensure they create a better interior environment for their building end users.
Sr. Building Envelope Consultant
Duffy Engineering
